The present invention relates to gas turbine engine bleed air, and in particular to the use of air bled from a gas turbine engine compressor.
In a typical gas turbine engine, a compressor compresses air and passes that air along a primary flow path to a combustor which mixes fuel with the compressed air and combusts the mixture. The combusted mixture expands and is passed to a turbine which is forced to rotate. When used on an aircraft, the primary purpose of this system is to provide propulsive force for the aircraft.
In some gas turbine engines, a portion of the air compressed by the compressor is diverted from the primary flow path to a bleed passage of a bleed air system. This bleed air is typically used for a variety of purposes, such as to de-ice a wing or to provide pressurized air to a cabin of the aircraft. Because the bleed air is often at an undesirably high temperature, a heat exchanger is used to cool the bleed air. Bleeding off and cooling compressed air typically does not generate thrust or useful work, thus reducing the efficiency of the compressor and the entire gas turbine engine. Moreover, the heat exchanger takes up a relatively large amount of space and undesirably increases the overall weight of the bleed air system.